hatchlings

Rainfall and sea turtles

October 4, 2024 By EarthWise Leave a Comment

There are seven species of sea turtles that inhabit the world’s oceans. Six of the seven sea turtle species – all of them except the flatback – are present in U.S. waters, and are listed as threatened or endangered under the Endangered Species Act.

Sea turtles, which have been around for more than 100 million years, spend the majority of their lives in the ocean, but they do periodically come ashore to nest. Female sea turtles lay their eggs in the sand and then return to the ocean. Survival odds for sea turtle hatchlings are quite bleak. In fact, only one out of every 1,000 makes it to adulthood.

Research shows that both air and sand temperatures are critical for sea turtle hatchling development. Cooler temperatures produce larger, heavier hatchlings with more males. Hatchling size matters because larger hatchlings, which can move faster, are more likely to survive because they spend less time on risky beaches. But rising temperatures might shorten incubation periods, and erratic rainfall can disrupt growth, potentially affecting survival.

A new international study by researchers from Florida Atlantic University and the University of Tübingen in Germany found that fluctuating rainfall patterns have a greater impact than changes in air temperature on sea turtle hatchling development.

The results, which were recently published in the journal BMC Ecology and Evolution, reveal that the impact of rainfall varies between species. As climate change shifts rainfall patterns, the impact on sea turtle nesting sites suggests that global conservation strategies for some species – like loggerhead and green sea turtles – likely need to be updated.

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Rain or Shine? How Rainfall Impacts Size of Sea Turtle Hatchlings

Sea Turtle

Photo, posted August 27, 2015, courtesy of USFWS/Orsulak via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Satellites discovering penguins

February 20, 2024 By EarthWise Leave a Comment

The loss of sea ice in Antarctica has forced emperor penguins to seek out new breeding grounds. Some colonies have traveled more than 20 miles in search of stable ice. Emperor females lay a single egg on a stretch of sea ice at the start of winter and males keep the eggs warm while the females go hunting for up to two months to bring back food for their hatchlings.

Emperor penguins are the tallest and heaviest of all living penguin species. The loss of sea ice has led to unprecedented breeding failure in some emperor penguin colonies. Emperor penguins are not threatened by hunting, habitat loss, or other human-caused problems, but the changing climate could be their undoing.

Emperor colonies are easy to spot from above. The penguins are up to four feet tall and the droppings from large colonies stand out vividly against white snow. A careful study of satellite imagery has revealed four previously unknown colonies of emperor penguins along the edges of Antarctica. This is the first bit of good news about the penguins in quite a while. The new discoveries, reported in the journal Antarctic Science, brings the total number of known colonies to 66.

The new discoveries are encouraging, but emperor penguins remain at risk from the warming climate. Three of the four new colonies are small, with fewer than 1,000 birds. So, the discovery does not have a big impact on the overall emperor penguin population. The addition of the new colonies is overshadowed by the recently reported colony breeding failures resulting from early and rapid ice losses.

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Thousands of Emperor Penguins Discovered by Satellite

Photo, posted January 19, 2014, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lots of female turtles

November 3, 2023 By EarthWise Leave a Comment

Green sea turtles were listed under the Endangered Species Act in 1978. Since that time, there have been conservation measures put in place in many locations. One such place is Florida, where restrictions on beachfront development and careful monitoring of turtle nests has helped to get hatchlings safely into the water. A gill net ban in 1995 sharply reduced the number of young turtles killed by fishing gear.

All of this has resulted in what is described as an explosion in turtle populations in Florida. Volunteers monitoring the 2023 nesting season on Florida’s beaches have counted more than 74,000 nests. That beats the previous record – set in 2017 – by an incredible 40%.

Unfortunately, this does not represent a guaranteed great future for the species. Sea turtles are particularly sensitive to the warming climate. The sex of a baby sea turtle is not determined by DNA, but rather by the temperature of the sand in which its egg develops. Cooler temperatures mean more males; warmer ones mean more females.

In recent years, the proportion of male green sea turtles has dwindled substantially. In the past few seasons, between 87 percent and 100 percent of the hatchlings tested in Florida have been female.

In the short term, the skewed sex ratio might be a boon for the species. Lots of females laying lots of eggs means lots of turtles. Sea turtles don’t reach sexual maturity until their twenties or thirties. So, for the next few decades, there are likely to be growing numbers of turtle nests. But down the line, there is going to be a real problem. Where will for all the female turtles find the mates to populate the species in the future?

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Florida Turtle Nests Are Recovering. When They Hatch, Expect Mostly Girls.

Photo, posted October 5, 2011, courtesy of Keenan Adams / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Not All Eggs In One Basket | Earth Wise

March 2, 2021 By EarthWise Leave a Comment

Sea turtles lay their eggs in burrows on sandy beaches. Many species lay their eggs on the exact same beach year after year. On average, sea turtles lay over 100 eggs in a nest and produce between 2 and 8 nests per season.

Animals that produce such large numbers of eggs have this reproductive strategy because so few survive to adulthood. Sea turtle eggs and hatchlings face numerous threats including powerful storms, poachers, marauding birds, and more. Estimates are that only one in thousand sea turtle eggs leads to an adult turtle.

A recent study by the University of South Florida looked at the reproductive strategy of loggerhead sea turtles nesting on Keewaydin Island off the southwestern Gulf coast of Florida. The researchers found that individual females lay numerous clutches of eggs in locations as much as six miles apart from each other to increase the chance that some of their offspring will survive.

As the saying goes, nesting loggerhead turtles don’t lay all their eggs in one basket. The researchers compare the turtles’ strategy to investing in a mutual fund. The female turtles divide their resources among many stocks rather than investing everything in a single stock.

During their 50-year lifetime, a single female loggerhead will produce over 4,000 eggs and scatter them at 40 different sites. This strategy helps reduce the risk of complete reproductive failure caused by hurricanes and thunderstorms that could wash out or flood all their clutches. The combination of unpredictable patterns of nests over time and space results in nearly two-thirds of loggerhead sea turtle hatchlings making it into the Gulf of Mexico. The species still faces significant challenges but it is doing its part to try to survive.

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Not all in one basket: Loggerhead sea turtles lay eggs in multiple locations to improve reproductive success

Photo, posted January 27, 2012, courtesy of Jeroen Looye via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sea Turtles Prospering During The Shutdown | Earth Wise

May 14, 2020 By EarthWise Leave a Comment

Our stories often discuss how human activities change the natural environment. With most of us confined to our homes, the lack of human activities is having profound effects on the environment. We are talking about some of these this week.

Seven different species of sea turtles are found in the world’s oceans and play important roles in marine ecosystems. Over time, human activities have tipped the scales against the survival of these animals. They have been hunted for their eggs, meat, skin, and shells and face habitat destruction and accidental capture in fishing gear. Their nesting grounds in beaches are constantly disturbed and endangered by human activity.

With the beaches in Florida closed in the effort to stop the spread of coronavirus, there is less plastic waste, fewer people and vehicles, and fewer artificial lights on the beach that disorient emerging turtle hatchlings. Because of all of these factors, sea turtles have been building their nests without disruptions.

In April, it was nesting season for leatherback turtles, the largest of all sea turtles. In May, loggerhead turtles arrive in Florida. Later in the summer, green turtles will arrive.

It takes about 60 days for sea turtle eggs to incubate and to hatch. During that period, lots of things can happen to a nest on an active beach – it can get trampled, people can dig it up, and artificial light can confuse the hatchlings as they try to find their way to the water. With the current shutdown, it should be a productive nesting season for sea turtles.

On the other hand, when beaches reopen, there may well be a major influx of people flocking to the beach because they have been stuck indoors for an extended period of time.

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Sea turtles are thriving as coronavirus lockdown empties Florida beaches

Photo, posted August 9, 2016, courtesy of Florida Fish and Wildlife via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.